Wednesday, May 30, 2007

Chad's New and Hot (Week 9)

For this week, I found two articles that both talk about speciation as a result of animal behavior. The first dealt with the speciation of tropical fish based on the tendency of coral reef fish to associate with fish of the same color. The study, performed by Oscar Puebla of McGill University, tracked the behavioral patterns of coral reef fish in dives for periods of one hour.

“Predatory Hypoplectrus fish were observed tracking other non-predatory fish species with similar color patterns to surprise their prey, which are usually not afraid of non-predatory fish species. They were also observed mating with partners with similar color patterns. Having identified behaviours that segregate the fish into groups and small but statistically significant genetic differentiation, the researchers concluded that each of the 13 color morphs of hamlet fish classifies as an incipient species.”

The reasons for this color-specific behavior are yet unknown, but Dr. Frederic Guichard, an assistant professor at McGill, claimed in the article that this showed a new possible means of speciation based not on physical mechanisms (like Darwin’s finches) but on rare behavior.

The other article discussed the link between the evolution of trichromatic vision (the ability to distinguish between red, green, and blue) and the development of primates with red skin and hair. Originally this ability was used to forage for ripe fruit and young foliage. However, by careful study of a phylogenic tree that tracked and linked this evolutionary ability to sexual selection.

“They found that the species that could discern red and orange hues were more likely to develop red and orange skin and hair, as well as highly social habits that make it easier to visually compare mates. In fact, the more social the trichromats are, the more red coloring they show.”

I found these two random articles pretty cool because they demonstrate two of the main points that keep coming up in class: First, the more that we understand about the development of traits and species, the more links that we find to Darwin’s theories of natural and sexual selection. Second, they remind readers that evolution is an constant, ongoing process. Here are the links to the two articles on coral reef fish and trichromatic vision.